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Old 10-03-06, 02:15 PM   #1
surreal
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what am i doing wrong? sorta long question on drivetrAIN

ok, i'm building this bicycle, and i'm mix-n-matching some parts, but all my research tells me that everything should be compatible. but, it's not. here's what the drivetrain looks like:

-ultegra 8spd barcons
-deore front derailleur (the one that can be set up for either top or bottom pull, with a 48t max chainring)
-XD's with 48/36/26 rings, 118mm bb spindle
-deore LX low-normal rear derailleur.
-HG70 11-30 cassette
ok, first thing i found out is that, despite rumors to the contrary, low-normals and ibarcons on index arent really compatible. at least, they don't seem to be. they work, but they dont work properly. friction has worked out ok, though.

the *real* problem is with shifting the front. the left barcon doesnt seem to have enough travel to swing the front derailluer sufficiently for 3 gear changes. i've been able to set it up to shift as a double, on either the inside or the outside, but it isnt working for all 3, whch is curious, b/c it's s'posed to be triple compatible.

comparing the travel of the left(front) shifter to the right(rear) shifter, it seems like the front one doesn't wanna go down (which'd correspond to the inner ring) as much as the right one. is there some sort of lockout i've missed? is this comparitively limited amount of travel normally sufficient for changing into all 3 front gears?

this forum has been a tremendous help to me in the past. any further help would be greatly appreciated. fwiw, i'm just now returning to the geared world after a 4 year fixed-only hiatus, and i hadn't a clue about anything back in my geared days, so much of this is new to me.

-rob
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Old 10-03-06, 04:10 PM   #2
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Have you tried it with a road group front deailleur?
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Old 10-03-06, 04:18 PM   #3
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My Ultegra barcon worked fine with both and an old LX and a new XT front derailleurs. The range is there......check again. Can you manually move the derailleur cage over all 3 chainrings? Are you sure you 'assembled' the barcon parts correctly?
Also, regardless of if your cassette is a 7 or 8 speed your 8 speed barcon should index regardless of rapid rise or low normal derailleur.

There is absolutely no reason why your setup shouldn't work.....they're all compatible.

Last edited by roadfix; 10-03-06 at 05:22 PM.
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Old 10-03-06, 05:06 PM   #4
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Back the limit screw all the way out so the derailleur has max extension then grab the cable and give it a firm pull. If the derailleur doesn't extend far enough out then it isn't compatible with your chainring setup. Otherwise, you don't have enough initial cable tension set.
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Old 10-03-06, 05:15 PM   #5
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I am presuming the shifters are in index mode when you try to shift. Sheldon Brown has a segment on how you can overcome the slight difference in cable pull between road shifters and mountain derailleurs by anchoring the cable at the derailleur bolt with a different orientation.

Other than that, try the derailleur limit screws.
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Old 10-03-06, 06:37 PM   #6
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From your comment about the shifter travel I agree with The Fixer, check your assembly of the left side shifter. Assuming you have checked the limit screws as others have said.
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